Engineering - Exam Papers - OL - Paper - 1991
200 Marks
Answer Question 1, Sections A and B and THREE other questions.
Section A - 30 Marks
Give brief answers to any six of the following :
| (a) |
Differentiate between electrical
conductors and insulators. |
| (b) |
List three types of
screw thread form. |
| (c) |
What is haematite? |
| (d) |
Give two safety precautions
for the use of power tools. |
| (e) |
Define tolerance as used in
a system of limits. |
| (f) |
Specify two copper
alloys. |
| (g) |
What is meant by the term Computer
Numerical Control (CNC)? |
| (h) |
What safeguards are required related
to a welding environment? |
Section B - 35 Marks
Answer any three of the following :
| (i) |
Describe the construction and operation
of any type of screw jack? |
| (j) |
Explain two of
the computing terms: byte, pixel, main memory,
floppy disk. |
| (k) |
Describe three methods of operating pneumatic valves. |
| (l) |
Explain two of
the terms: printed circuit board, silicon
chip, light emitting diode (LED), pyrometer,
reduction gear. |
| (m) |
Explain the purpose and use of
the mechanism shown in the diagram. |
|
| (a) |
Describe, with the aid of a diagram,
the cupola furnace and state its purpose. |
| (b) |
Identify the three grades of carbon steel, giving details of
composition and properties. |
| (c) |
Indicate, with reasons, the materials
used in the manufacture of any four of the following:
table lamp; lathe bed; light switch; hacksaw
blade; rainwater pipe; pressure cooker. |
| (a) |
What is work hardening? Explain
how the condition may be treated. |
| (b) |
Describe the heat treatment to
produce a hard surface on a mild steel component. |
| (c) |
How is furnace temperature measured?
Give a brief account of the method. |
| (a) |
State the advantages and disadvantages
of electric arc welding over oxy-acetylene
welding. |
| (b) |
What are the effects of setting
the welding current |
| (i) |
too high and |
| (ii) |
too low, |
| when arc welding? |
| (c) |
Explain the type of flame produced
with each of the following gas settings: |
| (i) |
excess oxygen; |
| (ii) |
excess acetylene; |
| (iii) |
correct balance between oxygen
and acetylene. |
OR |
| (c) |
Explain how the pneumatic
circuit shown operates.
Give an example of the use of such
a circuit. |
|
| (a) |
Explain the process of plastic
dip coating. |
| (b) |
What are the main differences
between thermoplastics and thermosetting plastics? |
| (c) |
Give an example of a product
of blow moulding and describe the process
briefly. |
| (a) |
Describe the type of work machined
in a centre lathe for each of the following
cases: |
| (i) |
between centres; |
| (ii) |
faceplate; |
| (iii) |
four-jaw independent chuck. |
| (b) |
What are the effects of setting
the lathe cutting tool: |
| (i) |
above centre; |
| (ii) |
below centre. |
| (c) |
Describe one of the following
machining processes: |
| (i) |
turning; |
| (ii) |
milling. |
| The action of the machine should
be clearly explained. |
OR |
| (c) |
Explain any three of
the following CNC terms: |
| (i) |
tool off-sets; |
| (ii) |
stepper motor; |
| (iii) |
canned cycle; |
| (iv) |
peck drilling. |
| (v) |
peck drilling. |
| (a) |
Explain the difference between
measuring and gauging.
List three gauges and three measuring tools
for precision measurement. |
| (b) |
Define |
| (i) |
clearance, |
| (ii) |
transition
and |
| (iii) |
interference fits. |
| (c) |
Describe the purpose of the following
tools: |
| (i) |
reamer; |
| (ii) |
surface plate; |
| (iii) |
vernier callipers. |
OR |
| (c) |
Explain how the power
supply circuit shown in the diagram
operates. |
|
